1. Field of the Invention
The present invention relates to an aromatic liquid crystalline polyester film.
2. Background of the Invention
Aromatic liquid crystalline polyester has been widely used for precision parts of electronic devices such as connectors obtained by injection molding, since liquid crystalline polyester shows low moisture absorption, excellent dielectric property at high frequency, heat resistance, and mechanical strength. Recently, it is explored that a film of aromatic liquid crystalline polyesters molded by extrusion process or tubular process in used for insulating films of multi-layer printed wiring boards or flexible printed wiring board.
However, the film of aromatic liquid crystalline polyester produced by extrusion process or tubular process has large anisotropy, resulting in weak tear strength along the direction perpendicular to the flow direction during molding and film handling, and resulting in easily tearing the film.
Accordingly, it is proposed that an aromatic liquid crystalline polyester film is obtained by casting an aromatic liquid crystalline polyester solution composition containing an aromatic liquid crystalline polyester and a halogen-substituted phenol on a substrate and removing the solvent (JP 2002-114894 A). However in the case where the polyester film is laminated on a substrate of a metal foil such as a copper foil or a resin film, it is still desired to improve the adhesion between the polyester film and the substrate.